Insulation materials for a vacuum insulated structure and methods of forming

Abstract

A method of forming an insulation material for a vacuum insulated structure includes heating glass flakes to at least a glass transition temperature of the glass flakes to induce a phase separation of the glass into an acid insoluble silica phase and an acid soluble phase. The glass flakes can be derived from a glass composition containing (by weight): SiO 2 from about 40% to about 80%, B 2 O 3 from about 10% to about 40%, Na 2 O from about 1% to about 10%, Li 2 O from about 0% to about 3%, CaO from about 0% to about 10%, ZnO from about 0% to about 5%, P 2 O 5 from about 0% to about 10%, and Al 2 O 3 from about 0% to about 10%. The method also includes a step of etching the glass flakes to dissolve the acid soluble phase to form porous glass flakes.

What is claimed is: 
     
         1 . A method of forming an insulation material for a vacuum insulated structure, comprising:
 heating glass flakes to at least a glass transition temperature of the glass flakes to induce a phase separation of the glass flakes into an acid insoluble silica phase and an acid soluble phase, wherein the glass flakes are derived from a glass composition comprising (by weight):
 SiO 2  from about 40% to about 80%, 
 B 2 O 3  from about 10% to about 40%, 
 Na 2 O from about 1% to about 10%, 
 Li 2 O from about 0% to about 3%, 
 CaO from about 0% to about 10%, 
 ZnO from about 0% to about 5%, 
 P 2 O 5  from about 0% to about 10%, and 
 Al 2 O 3  from about 0% to about 10%; and 
   etching the glass flakes to dissolve the acid soluble phase to form porous glass flakes.   
     
     
         2 . The method of  claim 1 , further comprising:
 combining the porous glass flakes with at least one of fumed silica, perlite, precipitated silica, aerogel powder, silicon carbide, carbon black powder, graphite, rice husk, ash powder, diatomaceous earth, and cenospheres.   
     
     
         3 . The method of  claim 2 , wherein the step of combining the porous glass flakes with at least one of fumed silica, perlite, precipitated silica, aerogel powder, silicon carbide, carbon black powder, graphite, rice husk, ash powder, diatomaceous earth, and cenospheres further includes the porous glass flakes having an aspect ratio of from about 100 to about 2,000. 
     
     
         4 . The method of  claim 2 , wherein the step of combining the porous glass flakes with at least one of fumed silica, perlite, precipitated silica, aerogel powder, silicon carbide, carbon black powder, graphite, rice husk, ash powder, diatomaceous earth, and cenospheres further includes the porous glass flakes having an average thickness of from about 10 nm to about 10 μm. 
     
     
         5 . The method of  claim 1 , further comprising:
 heating the glass flakes to a temperature less than the glass transition temperature of the glass flakes one of prior to the etching or subsequent to the etching to deform a shape of the porous glass flakes.   
     
     
         6 . The method of  claim 1 , further comprising:
 applying at least one opacifier including transition metal oxides from about 0% to about 10% to the glass composition.   
     
     
         7 . The method of  claim 6 , wherein the step of applying at least one opacifier further includes selecting the opacifier from magnesium oxide, cobalt oxide, and carbon black powder. 
     
     
         8 . An insulation material for a vacuum insulated structure, comprising:
 porous glass flakes comprising an acid insoluble silica phase;   at least one opacifier; and   at least one filler material.   
     
     
         9 . The insulation material of  claim 8 , wherein the at least one filler material is selected from fumed silica, perlite, precipitated silica, aerogel powder, silicon carbide, carbon black powder, graphite, rice husk, ash powder, diatomaceous earth, cenospheres, and combinations thereof. 
     
     
         10 . The insulation material of  claim 8 , wherein the at least one opacifier is incorporated into the porous glass flakes. 
     
     
         11 . The insulation material of  claim 8 , wherein the at least one opacifier is selected from magnesium oxide, cobalt oxide, and carbon black powder. 
     
     
         12 . The insulation material of  claim 8 , wherein the porous glass flakes have an aspect ratio of from about 100 to about 2,000. 
     
     
         13 . The insulation material of  claim 8 , wherein the porous glass flakes have an average thickness of from about 10 nm to about 10 μm. 
     
     
         14 . The insulation material of  claim 8 , wherein the porous glass flakes are combined with fumed silica. 
     
     
         15 . A method of forming an insulation material for a vacuum insulated structure, comprising:
 heating glass flakes to induce a phase separation of the glass flakes into an acid insoluble silica phase and an acid soluble phase, wherein the glass flakes are derived from a glass composition comprising (by weight):
 SiO 2  from about 40% to about 80%; 
 B 2 O 3  from about 10% to about 40%; 
 Na 2 O from about 1% to about 10%; and 
 CaO from about 0% to about 10%; and 
   etching the glass flakes to dissolve the acid soluble phase to form porous glass flakes.   
     
     
         16 . The method of  claim 15 , further comprising:
 combining the porous glass flakes with at least one of fumed silica, perlite, precipitated silica, aerogel powder, silicon carbide, carbon black powder, graphite, rice husk, ash powder, diatomaceous earth, and cenospheres.   
     
     
         17 . The method of  claim 15 , further comprising:
 heating the glass flakes to a temperature less than the glass transition temperature of the glass flakes one of prior to the etching or subsequent to the etching to deform a shape of the porous glass flakes.   
     
     
         18 . The method of  claim 15 , further comprising:
 applying at least one opacifier including of transition metal oxides from about 0% to about 10% to the glass composition.   
     
     
         19 . The method of  claim 18 , wherein the step of applying at least one opacifier further includes selecting the opacifier from magnesium oxide, cobalt oxide, and carbon black powder.